Sealing device for a rolling contact bearing

ABSTRACT

Sealing device for a rolling contact bearing ( 2 provide with a first shield ( 5 ) and a second shield ( 7 ) which are made of metal material and which are respectively coupled to an outer race ( 4 ) and an inner race ( 3 ) of the rolling contact bearing ( 2 ) itself, and a seal ( 10 ) which is made of synthetic material and which is integral to the first shield ( 5 ) and which presents a sealing lip ( 11 ) which is arranged substantially in contact with the second shield ( 7 ); the first shield ( 5 ) is defined by a cylindrical portion ( 15 ) which is assembled on the outer race ( 4 ), and the seal (10) is anchored to the cylindrical portion ( 15 ) in order to freely extend from and overhand the cylindrical portion ( 15 ) itself and it presents in axial section, a tapering shape towards a cylindrical sliding surface ( 13 ) of the second shield ( 7 ).

DESCRIPTION

[0001] The present invention relates to a The present invention relatesto a sealing device for a rolling contact bearing.

[0002] Sealing devices of a well-known type are assembled between aninner race and an outer race of a rolling contact bearing in order toprevent the entry of solid impurities and the leakage of lubricant andthey usually comprise a first shield which is made of metal material andwhich is coupled to the outer race, a second shield which is made ofmetal material and which is coupled to the inner race and is frontallyarranged to the first shield, and a seal which is made of syntheticmaterial and which is integral to the first shield and which is providedwith a sealing lip which extends between the two shields and which isarranged substantially in contact with at least one cylindrical slidingsurface of the second shield.

[0003] The first shield comprises an annular portion which extendstransversely to the cylindrical surface and which is substantiallyintegral with the seal apart from the sealing lip, which defines theonly axially free element of the seal itself. This kind of structurelimits the elastic characteristics of the sealing lip, on which,therefore, an annular spring is assembled which is suitable formaintaining the sealing lip itself in contact with the sliding surfacein such a way as to overcome any eventual errors of assembly and anywear in the seal due to friction arising from its contact with thecylindrical surface itself.

[0004] Sealing devices of the kind which has just been described haveproved to be extremely reliable, but they have presented somedisadvantages which are mainly due to the presence of the annularspring, the reduced dimensions of which do not permit an appropriatemodulation of the contact pressure of the sealing lip on the slidingsurface with the result that the effective working life of the sealitself is reduced. In addition, it has been discovered that the assemblyof the second shield frequently causes rotation errors in an axialdirection of the second shield itself with the result that the sealingcharacteristics and working life of the seal are reduced even further.

[0005] The aim of the present invention is to produce a sealing devicefor rolling contact bearings which will solve the above-mentionedproblems in a simple and cost-effective fashion.

[0006] According to the present invention, a sealing device for arolling contact bearing will be produced comprising an inner race and anouter race which are coaxial to each other and a rotation axis of therolling contact bearing itself; the device comprises a first shield madeof metal material which is coupled to the external race, a second shieldmade of metal material which is coupled to the inner race and a sealmade of synthetic material which is integral to the first shield andwhich is provided with a sealing lip which is substantially arranged incontact with the second shield; the device is characterised by the factthat the first shield is defined by a cylindrical portion which isassembled on the outer race of the rolling contact bearing; the saidseal is anchored to the cylindrical portion in order to freely extendfrom and overhang the cylindrical portion itself, and it presents, inaxial section, a tapering shape towards a cylindrical sliding surface ofthe second shield.

[0007] The invention will now be described with reference to theattached drawing which illustrates, in axial section and with some partsremoved for reasons of clarity, a preferred form of embodiment of thepresent invention which is provided as an example and which is in no waylimiting.

[0008] With reference to FIG. 1, the number 1 indicates a sealing devicein its entirety for a rolling contact bearing 2 comprising an inner race3 and an outer race 4 which are coaxial in relation to each other and toa rotation axis A of the rolling contact bearing 2 itself.

[0009] The device 1 comprises a first shield 5 which is made of metalmaterial and which is assembled under an internal cylindrical surface 6of the outer race 4, a second shield 7 which is made of metal materialand which is assembled under/below an external cylindrical surface 8 ofthe inner race 3, and a seal 10 which is made of synthetic material andwhich is integral to the first shield 5 and which is provided with asealing lip 11 which is arranged substantially in contact with thesecond shield 7.

[0010] The second shield 7 comprises a cylindrical portion 12 which isassembled in contact with the surface 8 and which is radially limitedtowards the outside by a sliding surface 13 and a flange 14 which istransverse to the portion 12 and which is arranged to face the outsideof the rolling contact bearing 2.

[0011] Instead, the first shield 5 comprises a cylindrical portion 15which is assembled in contact with the surface 6 in a frontal positionto the portion 12, and a flange 16 which is transverse to the portion 15and which presents a radial development which is considerably less thana radial development of the flange 14.

[0012] The seal 10 is anchored both to the flange 16 and the cylindricalportion 15 in order to freely extend from and overhang the cylindricalportion 15 itself. In particular, the seal 10 comprises a base body 17which is anchored in a radial direction to the cylindrical portion 15and in an axial direction to the flange 16, a sealing lip 11 which isarranged in substantial contact with the second shield 7, and anintermediate connecting body 19 of the lip 11 to the body 17.

[0013] The body 19 presents a lateral notch 20 which is axially opentowards the inside of the rolling contact bearing 2, and which isaxially defined towards the outside of the rolling contact bearing 2itself by a flat surface 21 which is transverse to the axis A. The notch20 is arranged so as to be axially aligned to the flange 16 and,therefore, it limits the radial development of the flange 16 itself. Inaddition, the body 19 presents, in axial section, a tapering shapetowards the sliding surface 13, and it is axially limited on theopposite side of the surface 21 by a tapered surface 22 which isarranged with its concave section towards the outside of the rollingcontact bearing 2.

[0014] On the part of the flange 16 which is not anchored, the body 17is radially limited towards the inside by a cylindrical surface 23,which is connected to the surface 22 by a cylindrical connecting surface25 with a curved generating line, and which defines, with an upper edge26 of the flange 14, an annular window 27. The window 27 and thearrangement of the connecting surface 25 and the surface 22 all combineto facilitate the expulsion of contaminating agents from inside thedevice 1 when it is in use.

[0015] The sealing lip 11 is substantially U-shaped with its own concaveportion turned towards the outer race 4 and towards the outside of therolling contact bearing 2, and it comprises a first arm 29 which extendsfrom the connecting body 19 towards the sliding surface 13, and a secondarm 29 which extends from the surface 13 towards the flange 14, withwhich it comes into contact.

[0016] The second arm 29 presents a thickness which is substantiallyconstant along the whole of its length, while the first arm 28 presentsa thickness which decreases as it extends towards the surface 13, and incorrespondence to its junction with the second arm 29 it presents athickness which is even greater to that of the second arm 29 itself insuch a way as to form a sharp annular edge 30 which is arranged incontact with the surface 13.

[0017] On the part opposite that which presents the sharp edge 30, thefirst arm 28 is limited by a curved surface 31 which is connected to thesurface 22, while the second arm 29 is radially limited towards theinside of the seal 10 by a respective curved surface 32 which isconnected to the surface 31, and by a flat surface 33 which is connectedto the surface 32, and, radially towards the outside of the seal 10, bytwo flat surfaces 34 and 35, of which the surface 34 is used in theformation of the sharp edge 30, and the surface 35 is parallel to thesurface 33 and forms an obtuse angle with the surface 34.

[0018] In correspondence with the free end of the arm 29, the surfaces34 and 35 are joined to each other by a further flat surface 36 whichdefines, with the surface 35, a bevelled sharp edge 37 which forms acontact between the lip 11 and the flange 14.

[0019] When the device 1 has been pre-assembled in such a way that theseal 10 is already arranged in contact with the second shield 7, and insuch a way that the two cylindrical portions 12 and 15 are substantiallyaligned in an axial direction, the device 1 itself is assembled onto therolling contact bearing 2 by inserting the first shield 5 under thesurface 6 of the outer race 4, and by inserting the second shield 7under the surface 8 of the inner race 3.

[0020] The assembly of the device 1 determines the positioning of theseal 10 in a working configuration, in which the lip 11 becomessubstantially squashed and is arranged, with the sharp edges 30 and 37,in contact with the surface 13 and the flange 14 and in which theconnecting body 19 is subjected to a degree of flexure such that thefibres arranged in correspondence to the flexed surface 22 are intraction while the fibres arranged in correspondence to the surface 21are compressed. The resistance of the body 19 to flexure determines a“spring effect” on the lip 11 which, therefore, is pushed furthertowards the second shield 7. The “spring effect” will last throughoutthe useful working life of the device 1 and will thus guarantee, on theone hand, that the seal 10 will not wear out due to friction and, on theother hand, that the friction itself will be reduced and modulated withthe result that the working life of the device 1 itself will beconsiderably prolonged.

[0021] In fact, the shape of the body 19 and the fact that it isinherently possible for it to flex freely without any further structuralconstraint and, finally, the fact that the body 19 and the lip 11 behavein different ways in terms of deformation, guarantee the contact betweenthe sharp edges 30 and 37 without reducing the sealing effect in any wayand make the lip 11 itself more elastic and modulate the contactpressure of the sharp edges 30 and 37 themselves while reducing theeffective working temperature and increasing the working life of thedevice 1.

[0022] The fact that the seal 10 can function independently to adapt itsown working configuration under different conditions of wear means,above all, that it can also overcome any eventual errors of assemblyconcerning the two shields 5 and 7, with the result that the assemblyitself becomes less problematical.

[0023] It is intended that the present invention should not be limitedto the form of embodiment herein described and illustrated, which isintended as an illustration of a form of embodiment of the sealingdevice for a rolling contact bearing, which may be subject to furthermodifications in terms of the shape and arrangement of its parts anddetails pertaining to its construction and assembly.

1. Sealing device (1) for a rolling contact bearing (2) comprising aninner race (3) and an outer race (4) which are coaxial to each other anda rotation axis (A) of the rolling contact bearing (2) itself; thedevice (1) comprises a first shield (5) made of metal material which iscoupled to the external race (4), a second shield (7) made of metalmaterial which is coupled to the inner race (3) and a seal (10) made ofsynthetic material which is integral to the first shield (5) and whichis provided with a sealing lip (11) which is substantially arranged incontact with the second shield (7); the device (1) is characterised bythe fact that the first shield (5) is defined by a cylindrical portion(15) which is assembled on the outer race (4) of the rolling contactbearing (2); the said seal (10)is anchored to the cylindrical portion(15) in order to freely extend from and overhang the cylindrical portion(15) itself, and it presents, in axial section, a tapering shape towardsa cylindrical sliding surface (13) of the second shield (7).
 2. Sealingdevice according to claim 1, characterised by the fact that the saidseal (10) comprises a lateral notch (20) which is axially open towardsthe inside of the rolling contact bearing (2) and which is axiallylimited towards the outside of the rolling contact bearing (2) by asmooth surface (21) which is transverse to the rotation axis (A). 3.Sealing device according to claim 2, characterised by the fact that thesaid first shield (5) comprises a flange (16) which is integral to thesaid cylindrical portion (15) and which is radially limited towards theinside of the said lateral notch (20).
 4. Sealing device according toclaims 2 or 3, characterised by the fact that the said seal (10)comprises a tapered surface (22) which is axially open towards theoutside of the rolling contact bearing (2) and which defines, togetherwith the said flat surface (21), a connecting section (19) between thesealing lip (11) and the cylindrical portion (15) of the first shield(5); the resistance of the connecting section (19) to determined flexureis such as to maintain the sealing lip (11) in contact with the slidingsurface (13) during variations in the working condition of the seal(10).
 5. Sealing device according to claim 4, characterised by the factthat the said seal (10) and the second shield (7) form an annular window(27) in relation to each other which faces the inside of the rollingcontact bearing (2) and, also in relation to each other, a connectingportion (25) of the said tapered surface (22) which enables the exit ofcontaminating agents from the sealing device (1) itself.
 6. Sealingdevice according to claim 4, characterised by the fact that the sealinglip (11) is substantially U-shaped, with its concave section turnedtowards the outer race (4) and towards the outside of the rollingcontact bearing (2), and it comprises a first arm (28) which extendsfrom the connecting section (19) towards the sliding surface (13), and asecond arm (29) which extends from the sliding surface (13) towards thesecond shield (7), with which it comes into contact; the first arm (28)presents a decreasing thickness as it extends towards the slidingsurface (13).
 7. Sealing device according to claim 6, characterised bythe fact that the first arm (28) presents, substantially incorrespondence with the second arm (29), an annular sharp edge (30)which is arranged under the sliding surface (13); the second arm (29)presents a substantially constant thickness along the whole of itslength.